Mr. Nimoy announced last year that he had the disease, which he attributed to years of smoking, a habit he had given up three decades earlier. He had been hospitalized earlier in the week.

His artistic pursuits — poetry, photography and music in addition to acting — ranged far beyond the United Federation of Planets, but it was as Mr. Spock that Mr. Nimoy became a folk hero, bringing to life one of the most indelible characters of the last half century: a cerebral, unflappable, pointy-eared Vulcan with a signature salute and blessing: “Live long and prosper” (from the Vulcan “Dif-tor heh smusma”).